Incretin hormones (GLP-1 and GIP) released from the intestine in response to meal ingestion augment insulin secretion from the pancreas to help maintain glycemic control. Studies in vitro and in vivo have shown that these incretin hormones also have functional effects in other tissues independent of the insulin secretory response. Both GLP-1 and GIP stimulate insulin secretion in a glucose-dependent manner, however the glucose-dependency of their extra-pancreatic effects has not been examined in vivo. By using pancreatic clamp methodology during euglycemic and hyperglycemic conditions we will test the hypothesis that extra-pancreatic effects of GLP-1 and GIP are glucose-dependent.